plug chop?

[chaz35]

I am riding around neighborhood and getting some fairly long WOT runs, thinking about doing a plug chop.  I have stock engine, 82 main jet, derestricted CDI and runs great.  Based upon how traffic moves around here, I am going 50mph for sure.  I can hear the engine go quite, so I think I am way past the power band, making max rpms (with wind at my back, going down a hill, drafting with traffic).

With a fairly short run, I am back at house after a long WOT run.  The engine is very crisp sounding, absolutely on smoke/ oil out of exhaust.  I running the oil pump, so at idle it's approx 100 to 1 fuel oil, so I am thinking a plug chop after I get home would probably give a good reading.  I guess I could test with a stricter plug chop and compare with a lazy one to see if any difference.  Just wondering if lazy would still give good results?

I know if running premix would be more critical to kill engine after WOT to do plug chop, but just seems with properly working oil pump wouldn't be as critical.

[CROSSBOLT]

What is a "plug chop"?

Karl

[chaz35]

You take out the plug and look at color, useful for tuning carb jetting.  Generally, looking for tan color, light color is too lean, dark/ oil on plug is too rich.   Too lean will damage your engine, too rich will not run it's best.  Cheers

[CROSSBOLT]

OK, got it! Just a difference in vernacular. Or, same language, different dialect. Something like that!

Karl

[gosku]

Remember that the spark plug does not change its color very fast, especially from darker to lighter. I believe it takes at least 100 mph to be sure that the color has changed. But given the fact that you haven't changed any settings lately, it could be a good time to check it out. Oh, and never check it after longer period of idling, the best is after a WOT run, just as you said.

"I know if running premix would be more critical to kill engine after WOT to do plug chop, but just seems with properly working oil pump wouldn't be as critical."
This one I don't understand  Do you mean that running on premix is safer when you have done the mods? I do believe so. But if the oil pump is working good and the plug chop is okay, I wouldn't worry about it.

Post your results of the plug chop! 

[chaz35]

With premix, you are always running the same oil ratio, so at idle you are running a lot more oil than is required, you are more likely to discolor the plug.  With the oil pump, you are running very little oil at idle.

I did pull the plug and it looked pretty good, definitely not too lean, not too rich, looked about right to me.  The door to access the plug makes it easy to pull the plug.  Cheers

[gosku]

Pulled out mine yesterday, after the whole winter. Looks like too rich, right?

[chaz35]

Yes, I would say maybe too rich, need new plug.  I would be looking for brown to tan.  Don't remember, what jets you running?

[BettinANDlosing]

Pulled out mine yesterday, after the whole winter. Looks like too rich, right?

More importantly what 2t oil you using? Looks like you might need to run a slightly hotter plug, BR7HSA, to burn the carbon off. The longer the WOT run, the hotter you want the plug.

[gosku]

New plug needed?  I bought this one last summer, and it's an iridium one, NGK BR8HIX. There is a thread about it on our forum too http://www.kymcoforum.com/index.php?topic=2353.0

But if you recommend changing for a new one I can install a new standard one as I have bought them as spare parts just in case, I have the NGK BR8HSA and the Denso equivalent, W24FR-L I believe. There should be no difference between them right?

Since approximately 1 year I'm using Motul Scooter Expert 2T Technosynthese, it's a semi synthetic oil. Before that, the engine was running on Orlen 2T semi synthetic, which is kind of low budget type of thing.
I've messed with carb screws and the current setting provides very nice performance, except it seems to be too rich when looking on the spark plug, but that still is better than too lean. But I've never messed with the jetting and have no clue what jets I'm running.

But I'm wondering now about something else... Before CVT upgrades I had to ride with WOT most of the time, but the engine was running on low RPM's especially on uphill roads, and the majority of roads here aren't flat. Now I don't need to ride with WOT all the time, and when I do, the RPM's are nice, so maybe now the color of the plug will change after some time?

Given the fact that I'm doing some bigger distances (since Monday 350 kilometers) would you recommend that I switch the plug to the slightly hotter BR7HSA?

[chaz35]

I am no expert on plugs, I often run them til they stop working, which on kart or minibike is no consequence.  I am more likely to change more often with scooter, since a fouled plug can leave me stranded out on the road.  I run the cheap recommended plug NGK BR8SHA and like it.  I need to order some more, last time as I recall cost less than $7 for 2 shipped to my door.

Running good oil is key IMO.  Checking the carb jets is a pain 1st time you do it, then becomes a routine task.  The hardest part was always taking off the airbox, when the weather warmed up a little it got easier, softened up the rubber flange.  Now I have air pods and they are easy to take off.

If you every add a pipe or air pod you will probably have to change carb jets.  If you are happy with the way yours runs, I wouldn't change a thing.  I started with the engine and worked on my CVT last.  Sounds like you started with your CVT 1st.  You may want to soup up engine a little more at some point.

I know not possible, but wish we were closer and could do some riding.  Then, if mine ran a little better you may be more motivated to change your jets, but maybe not.  My son-n-law has Super 8 150 and I have been modifying my 50's to run better with him.  If I wasn't riding with him, I would probably be less likely to mod mine.  Actually, the way my People 50 ran with just CDI derestricted was very impressive, but way slower than my Super 9 with Tecnigas pipe, so I was right away trying to make it faster.

These scooters are really fun.  Cheers

[gosku]

I read a little bit about the spark plugs today and I'm not convinced to change them to something that is not recommended by the manual. They say that the hotter plugs burn the carbon off easier, but they can damage the piston and are not good for longer runs. I will inspect it soon and maybe even swap for a new one just to see what color it will get. I'm happy with the Motul oil and I think it's good stuff.

I took off the airbox a few times, it was pretty easy. But there are so many lines to disconnect from the carb and I'm not sure how to unmount it from the vehicle, probably because I don't see the mounting very well because of all the dirt in that area lol.

I'm a second owner, when I bought the bike it was already derestricted and had some upgrades installed like the Tecnigas pipe and Givi case, probably had the carb rejetted too. CDI is derestricted. So yes, I started with CVT, but before me someone else started with other things 

I'm happy with the way it runs now, but yeah, it would be cool to be able to compare it with yours! I'm not sure if I'm wrong or right, but I think I'm currently as fast as 125 ccm four stroke, probably the top end being the only difference 

[chaz35]

I didn't realize you already had Tecnigas pipe, I am pretty sure carb was rejetted or it wouldn't run very well, would be too lean.  I bet yours runs just like mine, hauls butt!  I would say you are as fast as 125 4T for sure.  I am almost as fast as 150 4T, he can jump me off the line, and a little on top end, but mid range I may be faster.

Motul oil has very good reputation over here.  I just bought some MOTUL ESTER SYNTECTIC 2T Motul Snow Power 2-Stroke Snowmobile Oil 4L 1 GALLON, got it cheap, shipped from Canada.  Best I can tell, it's just like Motul's other full synthetic 2T oil, just packaged different.

Next time I will probably get a synthetic blend, I am beginning to think 100% synthetic is probably overkill for a street scooter engine that is run a little rich for safety.  I can get a gallon of good quality synthetic blend for approx $30 shipped, the good quality full synthetic is usually approx $50 shipped.

1st time I took carb off the scooter I cleaned it, checked the jets, changed main jet, and put it back together.  Now, if I am changing jets I take out the storage box so I can easily get to the carb.  Then, I take off the 2 nuts holding the carb to the manifold and slip it off.  Then I can take the bowl off and get to the jets and change them.  I don't have to disconnect any of the hoses, throttle cable, airbox, etc.  If area is dirty, you probably need to make sure all cleaned up before assembly, would be very easy to introduce some nasty dirt/ sand into the engine while working on it.

I know you have People S 50, so probably a little different from mine.  My Super 9 is easier to work on in some areas, but harder in others compared to my People 50.

[BettinANDlosing]

One plug hotter or cooler is totally fine, in fact all the old Honda two stroke service manuals list one colder and one hotter plug for certain riding conditions, more stop and go colder, more WOT hotter. One change won't hurt the piston, and looking at your plug you either need to rejet, or use a hotter plug because there is too much carbon on that plug. Also, with two strokes I don't mess around with Iridium plugs because the only reason to use iridium is plug life, which is automatically shorter on a two stroke so there is no benefit to using them. Buy a box of 10 BR8HSA and switch every 1000km.

[gosku]

Now, if I am changing jets I take out the storage box so I can easily get to the carb.  Then, I take off the 2 nuts holding the carb to the manifold and slip it off.  Then I can take the bowl off and get to the jets and change them.  I don't have to disconnect any of the hoses, throttle cable, airbox, etc.

Thanks! I didn't realize it can be that easy! I always thought I will have to remove the hoses and cables 

Motul has a good reputation in Europe too, it's not that expensive if you know where to buy, the one I'm buying costs around 7$ for 1 litre (33 oz).

Haha right, it hauls butt!  I overtake cars more often than they overtake me 


Thanks for the advice with the spark plugs! I won't invest in Iridium anymore, and will swap it for a new one soon. Might experiment with the hotter one too!

And here's a pic from a bigger trip yesterday, and you can see the hilly area where I ride  The windshield is a custom one, I cut it out myself. The bike is dirty, I know!